Assessing flexibility by ramping factor in power systems with high renewable energy proportion

Current flexibility assessment methods (FAMs) have limitations, such as difficulty in evaluating entire grids with static FAMs and challenges in grid planning with interval FAMs. While probability FAMs are commonly used for grid planning, they are unable to provide an analytical mathematical model, leading to slow and complex solutions. To address these issues, this paper proposes a ramping factor-based FAM. This method not only guides flexible planning of the entire grid but also offers simplicity and speed in its application. As the flexibility metric, the ramping factor can evaluate the flexibility of a node or a grid. The ramping factor of a local grid is defined by that of the generalized node in the higher-level grid, and the concept of the generalized node is from electrical grid theory. Building upon this, a mathematical model is developed to optimize the allocation of flexible resources, providing guidance for the planning of these resources in the local grid. The proposed method's feasibility and effectiveness are verified through a case analysis on an improved IEEE 30-Bus System with high renewable energy proportion, demonstrating its advantages over traditional probability assessment methods. (c) 2017 Elsevier Inc. All rights reserved.